Biofilm reduction in crossflow filtration systems

ABSTRACT

Systems and methods for reducing biofilms are described. The systems and methods are particularly suitable for use with conventional aqueous crossflow filtration systems, such as reverse osmosis systems. The addition of the enzyme/surfactant compound has been found to enhance the effectiveness of conventional crossflow filtration processes by decreasing or inhibiting the growth of biofilms and other contaminants.

FIELD OF THE INVENTION

[0001] The present invention relates to systems and methods forreduction and control of bacterial biofilm. More particularly, thepresent invention relates to systems and methods for reduction ofbiofilms in crossflow filtration systems.

BACKGROUND OF THE INVENTION

[0002] Biofilms are formed when colonies of bacteria aggregate onsurfaces in many different locations. When bacteria in biofilmaggregate, they produce a sugary, polysaccharide-containing mucouscoating, or slime. Bacteria grow and multiply faster when attached(sessile) than when free-floating (planktonic). Within the slime, thebacteria form complex communities with intricate architecture includingcolumns, water channels, and mushroomlike towers. These structuraldetails are believed to improve biofilm nutrient uptake and wasteelimination, as blood vessels do in an animal's body. More informationabout biofilms is provided in an article entitled “Sticky Situations:Scientists are Beginning to Understand How Bacteria Find Strength inNumbers” by Jessa Netting, published in Science News, 60:28-30, Jul. 14,2001, which is the basis for the information in this and the followingparagraphs, and which is hereby incorporated by reference herein in itsentirety.

[0003] Biofilms occur in a wide range of locations. Many are found on orin the human body, including on the teeth, gums, ears, prostate, lungs,and heart, where they are believed to be implicated in chronicinfections such as gum disease, ear infections, infections of theprostate gland and heart, and lung infections in people with cysticfibrosis. Biofilms also occur in nature, such as the slime that coversriver rocks, marshes, and the like. Biofilms also occur in medicalequipment, such as catheters, and are a major source of hospitalinfections. Biofilms can also occur in areas such as contact lenses,other medical equipment, and in other industries. A primary difficultywith biofilms is that they are more difficult to reduce or eliminatethan are individual bacteria. This is due to the formation of theprotective layer of slime, as well as adaptations that the individualbacteria undergo when they form biofilms.

[0004] One important area in which biofilms occur is in aqueous systemsthat use separation membranes, such as particle filtration,microfiltration, ultrafiltration, nanofiltration, and particularlyreverse osmosis (“RO”) systems. Microfiltration membranes are typicallypolymer or metal membrane disc or pleated cartridge filters rated in the0.1 to 2 micron range that operate in the 1 to 25 psig pressure range.Ultrafiltration is a crossflow process that rejects contaminants(including organics, bacteria, and pyrogens) in the 10 angstrom to 0.1micron range using operating pressure in the 10 to 100 psig range.Nanofiltration equipment removes organic compounds in the 200 to 1,000molecular weight range, rejecting selected salts. Reverse osmosisremoves virtually all organic compounds and 90 to 99% of all ions underpressure in the 200 to 1000 psig range.

[0005] These systems use membranes to selectively remove or separateextremely small substances from water and process streams inresidential, commercial, and industrial applications. When biofilm ispresent on the membrane due to microbial growth, colloidal solids andinsoluble precipitates can adhere to the sticky substance. As thiscombination builds, water transmission rates through the membrane arereduced and/or additional pressure must be applied to maintain the samewater transmission rates. Colloidal solids, microbiological growth, andinsoluble precipitates can collect on the membrane during operation.Conventional treatment methods include continuous dosing, in which aresidual level of a biocidal agent is maintained within the system, orperiodic cleaning and sanitization, in which the filtration system isshut down for a periodic cleaning and sanitization using biocidalagents, acids and caustics. Even with continuous dosing methods, at somepoint the filtration system must be shut down so that the membrane canbe cleaned or replaced. This results in downtime and consequentadditional operating expense. Moreover, the cleaning and biocidal agentsand caustics that are conventionally used to clean and sanitize thefiltration systems have the effect of degrading the filter membranes,which are typically comprised of polymers such as cellulose acetate orpolyamide polymers. A number of pre-treatment processes are alsoavailable to reduce the fouling potential of the feed water beingintroduced to the membrane. These include various types of filtration,disinfection, and chemical treatment. Even with these methods, however,most RO treatment systems must be cleaned regularly.

[0006] Accordingly, there exists a long-felt need for improved treatmentprocesses that can achieve reductions in biofilm, particularly in thearea of aqueous systems that use separation membranes.

SUMMARY OF THE INVENTION

[0007] The present systems and methods are directed to the use ofcompositions including enzymes and surfactants to obtain biofilmreduction. The enzyme/surfactant compound comprises a blend of enzymesand surfactants over a broad range of compositions and concentrationsdependent upon the biofilm treatment application. Additional optionalcomponents may include micronutrients that are generated during theenzyme production process or added as additional ingredients. Furtheroptional ingredients in the enzyme/surfactant compound include enzymestabilizers and anti-microbials to prevent product degradation.

[0008] The addition of the enzyme/surfactant compound has been found toenhance the effectiveness of crossflow filtration systems, particularlyreverse osmosis systems, by increasing throughput, maintaining orimproving efficiency, reducing biofilm, decreasing periodic maintenancerequirements, and decreasing the need for costly system shutdowns.

[0009] It is thus an object of this invention to provide systems andmethods for reducing biofilms.

[0010] It is a further object of this invention to provide systems andmethods for improving the performance of aqueous systems that useseparation membranes, thus enhancing the separation process of suchsystems.

[0011] It is a still further object of this invention to provide systemsand methods for reducing biofilm and other fouling agents in crossflowfiltration systems, thus enhancing the filtration process.

[0012] It is a still further object of this invention to provideimproved aqueous filtration systems and methods that reduce fouling.

[0013] These and further objects and advantages will become apparentupon consideration of the detailed description and drawings enclosedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a flow diagram illustrating a conventional reverseosmosis filtration system.

[0015]FIG. 2 is a graphical illustration of a membrane showing itsfunction of filtering an aqueous stream containing contaminants.

[0016]FIG. 3 is a graph showing flux vs. time for an aqueous crossflowfiltration system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The materials, systems, and methods of the present inventioninvolve the use of an enzyme/surfactant blend compound to reducebiofilms where they occur. The description below will focus on crossflowfiltration systems, particularly reverse osmosis systems. It should beunderstood, however, that the materials, systems, and methods describedherein have a broad range of applications, and are not limited solely tofiltration systems, crossflow filtration systems, or reverse osmosisfiltration systems.

[0018]FIG. 1 is a flow diagram illustrating a conventional reverseosmosis filtration system. Feed water (F) enters a first end of thevessel 10, and concentrate (C) exits from the opposite end of thevessel. A membrane system 12 will typically comprise a plurality ofspiral-wound membranes tightly wound within the vessel. A permeate tube14 is provided at the center of the vessel, surrounded by the membranesystem 12. As the feed water (F) enters the vessel 10, it encounters themembrane system 12. The permeate (P) passes through the membranes intothe permeate tube 14, where it eventually exits the vessel as indicatedin FIG. 1.

[0019]FIG. 2 is a graphical illustration of a membrane showing itsfunction of filtering an aqueous stream. The membrane includes a solidbarrier 16, usually formed of cellulose acetate, metal, or a polymersuch as a polyamide. Sub-microscopic pores 18 are sized to pass water 20while rejecting oil, dirt, and other contaminants 22. The pores alsoreject bacteria 24. A properly designed membrane and system allows onlydesired molecules to pass through the membrane barrier regardless of thefeed stream contaminant level.

[0020] As biofilm or other contaminants build up on a membrane system,the system performance will deteriorate. For example, the filtrationsystem may require an increased pressure differential to produce thesame flux as the system in its “clean” state. Stated otherwise, for thesame level of pressure differential, the flux rate of the system willdecrease. For these purposes, the term “pressure differential” or “DeltaPressure” refers to the difference in pressure between the feed stream(F) and the permeate stream (P), and “flux” refers to the flow rate ofthe permeate stream (P). This deterioration of performance isillustrated graphically in FIG. 3. For each cycle between periodiccleanings, the flux will gradually deteriorate over time as biofilm andother contaminants build up on the membrane system. The periodiccleaning will cause the flux level to increase, although typically notto its peak level from the previous cycle because the membrane willgenerally degrade due to use and, in most circumstances, due to thecleaning process. Thus, in addition to the fluctuations of the systemflux between periodic cleanings, there will also be an observed generaldecline in system performance over time, as illustrated in the paralleldownward sloping phantom lines in FIG. 3.

[0021] It has been found that the addition of an enzyme/surfactantcompound to the feed stream (F) has the effect of decreasing fouling ofthe filter system, and enhancing the filtration and concentrationprocesses of conventional filtration systems. The enzyme/surfactantcompound is a blend of enzymes and surfactants of a range ofcompositions and concentrations. The basic enzyme/surfactant compositionmay be supplemented with micronutrients generated during the enzymeproduction process or added separately. It is also possible tosupplement the enzyme/surfactant compound with stabilizers, compoundsthat give significant stability to the activity of the enzymes. Thecomposition may also optionally be supplemented with anti-microbialagents that inhibit the growth of microbes in its concentrated form.

[0022] Enzymes degrade pollutants of biological origin, such as fats,oils, proteins and polysaccharides. Other enzymes are known to degradehydrocarbons. Enzymes pre-digest pollutants so they may be more easilytaken up and degraded by bacteria. In its preferred form, theenzyme/surfactant compound may contain one purified enzyme or a broadspectrum of enzymes and enzymatic activities. Typical enzymes includedin the compound include lipases and esterases, phosphatases, proteases,glycosidases, cellulases, cellobiases, and polysaccharide hydrolases.Enzymes in the compound may also include enzymes with otherspecificities such as oxidative enzymes, and the composition of anenzyme cocktail used in the compound may be specifically formulated tomeet the needs of specific aqueous filtration applications. Anonlimiting list of enzymes and enzyme activities believed to be usefulin the enzyme/surfactant compound includes the following: alkalinephosphatase, esterase (C-4), esterase-lipase (C-8), lipase (C-14),leucine arylamidase, valine arylamidase, cystine arylamidase, trypsin,chymotrypsin, acid phosphatase, naphthol-AS-BI-phosphohydrolase, alphagalactosidase, beta galactosidase, beta glucuronidase, alphaglucosidase, N-acetyl-beta-glucosaminidase, alpha mannosidase, and alphafucosidase.

[0023] There are a great many materials derived from plant, animal, andmicrobial sources that have been known to those skilled in the art to berich sources of enzymes. These source materials may be used with full,partial, or no purification of enzymes to obtain enzymes for use 5 inthe enzyme/surfactant compound. Some of these sources of enzymes areprovided in Table 1 below. Additional information concerning the sourcesof enzymes useful in the enzyme/surfactant compound may be found in:Thomas E. Barman, Enzyme Handbook, Vols. I-II (Springer-Verlag, New York1969); Dixon and Webb, Enzymes, pp. 671-785 (Academic Press Inc., 1964);Kornberg, For the Love of Enzymes: The Odyssey of a Biochemist, p. 37(Harvard University Press, 1989); Fruton and Simmonds, GeneralBiochemistry, pp. 218-219 (John Wiley and Sons, 2nd Ed. 1958); U.S. Pat.No. 4,891,320 to Aust et al.; and U.S. Pat. No. 3,635,797 to Battistoniet al. Each of these publications is hereby incorporated by referenceherein in its entirety. TABLE 1 SOURCE MATERIAL ENZYMES REFERENCE YeastExtract Invertase (Sucrase) Kornberg Catalase Fruton and SimmondsLactase Battistoni et al. Maltase Carboxylase Oxidative and Metabolicenzymes Malt Extract Amylase Kornberg Maltase Battistoni et al. DiastaseHen's Egg White Lysozyme Fruton and Simmonds Animal PancreasChymotrypsin Fruton and Simmonds Trypsin Plant Juices and Papain Frutonand Simmonds Resins Peroxidases Bacteria Glycoside Hydrolases Dixon andWebb Proteases and Peptidases Lipases Fungi Peroxidases Aust et al.

[0024] The extraction of enzymes from source materials may be enhancedby enzymatic activity. It is a well established practice to effect therelease of enzymes from yeast cells by autolysis, that is the use ofendogenous (yeast produced) enzymes to break yeast cell membranes. Therelease of enzymes may also be enhanced by the use of exogenous enzymes.For example, the addition of cellulases to malt increases the yield ofother hydrolytic enzymes derived from this source material. Beyond this,methods of obtaining or manufacturing enzymes or enzyme cocktails fromthese source materials are well-known in the art and are beyond thescope of this discussion, and will therefore not be repeated here. Allof the enzymes, endogenous, exogenous, and those released from sourcematerials may be incorporated into the composition so that it has asbroad a range of enzymatic activities as possible.

[0025] In a preferred form, the enzyme/surfactant compound includesenzyme activities from Esterases, such as esterase (C-4) andesterase-lipase (C-8); Proteases, such as cystine arylamidase andchymotrypsin; Glycosidases, such as beta galactosidase, betaglucoronidase, beta glucosidase, and alpha mannosidase; andPhosphatases, such as acid phosphatase andnaphthol-AS-BI-phosphohydrolase. It is believed that other and furtherenzymes may further enhance the effectiveness of the enzyme/surfactantcompound. Accordingly, this list should be considered illustrative andnot limiting.

[0026] Enzymes may be prepared by a number of methods known to thoseskilled in the art, including various fermentation processes. Enzymesfor use in the enzyme/surfactant compound may be prepared as an enzymecocktail derived from the fermentation product of molasses and diastaticmalt by Saccharomyces cerevisiae. Additional yeast strains that may beused instead of or in addition to Saccharomyces cerevisiae includeKluyveromyces marxianus, Kluyveromyces lactis, Candida utilis (Torulayeast), Zygosaccharomyces, Pichia, Hansanula, and others known to thoseof skill in the art. Micronutrients may be added to the process,including diammonium phosphate, ammonium sulfate, magnesium sulfate,zinc sulfate and calcium chloride. Additional micronutrients, such asvitamins and amino acids, are produced during the fermentation.

[0027] Surfactants that are useful in the enzyme/surfactant compound maybe either nonionic, anionic, amphoteric or cationic, or a combination ofany of the above, depending on the aqueous filtration application.Suitable nonionic surfactants include alkanolamides, amine oxides, blockpolymers, ethoxylated primary and secondary alcohols, ethoxylatedalkylphenols, ethoxylated fatty esters, sorbitan derivatives, glycerolesters, propoxylated and ethoxylated fatty acids, alcohols, and alkylphenols, glycol esters, polymeric polysaccharides, sulfates andsulfonates of ethoxylated alkylphenols, and polymeric surfactants.Suitable anionic surfactants include ethoxylated amines and/or amides,sulfosuccinates and derivatives, sulfates of ethoxylated alcohols,sulfates of alcohols, sulfonates and sulfonic acid derivatives,phosphate esters, and polymeric surfactants. Suitable amphotericsurfactants include betaine derivatives. Suitable cationic surfactantsinclude amine surfactants. Those skilled in the art will recognize thatother and further surfactants are potentially useful in theenzyme/surfactant compound depending on the particular aqueousfiltration application.

[0028] Preferred anionic surfactants used in the enzyme/surfactantcompound include CalFoam ES 603, a sodium alcohol ether sulfatesurfactant manufactured by Pilot Chemicals Co., and Steol CS 460, asodium salt of an alkyl ether sulfate manufactured by Stepan Company.Preferred nonionic surfactants used in the enzyme/surfactant compoundinclude Neodol7 25-7 or Neodol7 25-9, which are C₁₂-C₁₅ linear primaryalcohol ethoxylates manufactured by Shell Chemical Co., and Genapol7 26L-60, which is a C₁₂-C₁₆ natural linear alcohol ethoxylated to 60E Ccloud point (approx. 7.3 mol), manufactured by Hoechst Celanese Corp. Itshould be understood that these surfactants and the surfactant classesdescribed above are identified only as preferred materials and that thislist is neither exclusive nor limiting of the enzyme/surfactantcompound.

[0029] One or more additional components may optionally be added to theenzyme/surfactant compound in order to stabilize the compound andincrease shelf life. Such additional components may include enzymestabilizers, anti-microbial agents, and antioxidants.

[0030] Enzyme stabilizers are effective to extend the enzymatic activityof enzymes. Enzyme stabilizers can include sugars, polyhydrilicalcohols, other organic solvents, ionic or nonionic species, andpolymers. An example of a commonly used stabilizer is propylene glycol.

[0031] Examples of anti-microbial agents that may be used in theenzyme/surfactant compound include propylene glycol, methyl paraben,propyl paraben, and sodium benzoate.

[0032] Examples of antioxidants that may be incorporated into theenzyme/surfactant compound include butylated hydroxyanisole (BHA),butylated hydroxytoluene (BHT), ascorbic acid, and others.

[0033] It is preferable to adjust the pH of the enzyme/surfactantcompound to from about 3.75 to about 5.0, and most preferably to fromabout 4.2 to about 4.5, with phosphoric acid to help stabilize theproduct. In particular, it is beneficial to make the compound acidic inorder to optimize the activity of the anti-microbial agents, such asmethyl or propyl paraben.

[0034] A preferred composition of an enzyme/surfactant compound usefulin the systems and methods described herein is provided in Table 2below. TABLE 2 Concentra- Preferred tion Range Concentra- (% by tion (%Component Type Component weight) by weight) Solvent Water 25.0-90.063.92 Enzyme/Nutrient Enzyme Cocktail  5.0-60.0 20.0 Source(Fermentation product of molasses and diastatic malt by Saccharomycescerevisiae) Micronutrients Inorganic salts 0.05-2.50 0.31 (e.g.,diammonium phosphate, ammonium sulfate, magnesium sulfate, zinc sulfate,calcium chloride) Surfactant Neodol7 25-7  2.0-40.0 7.5 (Non-ionic)Surfactant (Anionic) Steol CS 460  0.5-20.0 2.5 Stabilizer Propyleneglycol  0.5-40.0 5.27 Anti-microbial agent Methyl paraben 0.03-0.5  0.15Anti-microbial agent Propyl paraben 0.01-0.3  0.05 Anti-microbial agentSodium benzoate 0.03-0.5  0.15 Antioxidant BHA 0.002-0.1  0.02Antioxidant BHT 0.002-0.1  0.02 Antioxidant Ascorbic acid 0.05-2.0  0.11TOTAL: 100.00

[0035] To achieve reduction of biofilm and other contaminants in areverse osmosis or other aqueous crossflow filtration system, anenzyme/surfactant compound, such as one having the composition listed inTable 2 above, is preferably added to a feed stream at a concentrationof about 0.1 parts per million (ppm) to about 25 ppm, depending on theparticular application and the contaminants of interest. Higher or lowerconcentrations may also be possible. A preferred concentration fortertiary treatment of municipal wastewater is from about 0.5 ppm toabout 5 ppm, particularly about 3 ppm. A cleaning cycle may be employedwherein the concentration is increased for a period of time. A preferredcleaning cycle includes a concentration of the enzyme/surfactantcompound of about 6 to about 25 ppm for a period of from about 3 toabout 12 hours. A particularly preferred cycle comprises a concentrationof about 9 ppm for a period of about 6 hours.

[0036] Experiments have shown that the use of the enzyme/surfactantcompound increases system performance by preventing fouling due tobiofilm and other contaminants. This result has been observed in twoways. Referring once again to FIG. 3, first, the flux rate betweensystem cleaning cycles has been observed to decrease less through use ofthe enzyme/surfactant compound. Second, the overall system performancehas been observed to degrade significantly less when theenzyme/surfactant compound has been used. It is believed that theincreased system performance may be due, at least in part, to abreakdown of the sticky polysaccharide biofilm material.

[0037] For example, studies were conducted to determine the effects oftreating sludge with the composition listed as the “PreferredConcentration” in Table 2. Sludge mass is made up of clumps of bacteria,held together by the sticky polysaccharide biofilm material. During thefiltration process, this creates a barrier film that does not allow thewater to freely drain from the sludge mass. Sludge was obtained from theOrange County (California, United States) Sanitation District for thestudy. Testing was conducted to determine TSS (Total Suspended Solids),COD (Chemical Oxygen Demand), and Filtration Characteristics, or waterretention. Baseline data, as well as treated and control were recorded,with the following results: Sludge Volume TSS (%) COD (ppm) Reduction(%) Baseline 3.82%  390 ppm N.A. Control 3.59% 2115 ppm 20.33% Treated3.59% 2590 ppm 14.53% % Change Over 0.00% +18.3% −28.5% Control

[0038] While the TSS levels were reduced by 7% for both the Treated andControl from the Baseline, the permeate from the Treated sampleexhibited an increase in COD of 18.3% over the Control. It is assumedthat the reduction in TSS occurred due to a decay of the actual cells orwalls. However, the COD results, in conjunction with the significantreduction of sludge volume for the Treated sample vis-a-vis the Control,establish that channeling in the sludge matrix is improved, allowing thewater to drain through (or around) the bacterial cell matter. This isdue to the breakdown of the sticky polysaccharide biofilm material.

[0039] The foregoing descriptions include a detailed description of theuse of an enzyme/surfactant compound for the treatment of wastewater ordrinking water in crossflow filtration systems. One example of suchsystems is water desalination. It has been found that theenzyme/surfactant compound, when used in a water desalination process,improves the efficiency of the desalination process.

[0040] In the wastewater or drinking water systems and methods describedherein, the filtrate is the “product” obtained from the permeate in theprocess. As yet another example, the methods described herein may alsobe used in applications where the concentrate is the “product.” Forexample, in the dairy, fruit juice, or other industries, concentrationprocesses are used to eliminate water from a feed stream. In those typesof systems and methods, the enzyme/surfactant compound may be used aspart of a cleaning cycle to effectively clean filter membranes withoutdamaging them as would be the case with strong acid or caustic cleaningmaterials. In those systems and methods, the enzyme/surfactant compoundis circulated/recirculated at a concentration of as low as 5-10 ppm toas high as 1% to 5%. The actual use levels would be highly dependent onthe nature of the foulant, time limits for the cleaning cycle,temperatures of the cleaning solutions, filter membrane constructionand/or materials, filter type (micro, ultra, nano, or reverse osmosis),and other factors. As a non-limiting example, the process ofconcentrating milk causes a significant buildup of not only biofilm onthe filter membranes but also significant quantities of butter fat, oil,protein, and other milk constituents. In that example, a circulation ofa cleaning solution of about 1% to 2% of the enzyme/surfactant compoundis utilized at a temperature of 100° F. or higher for as little as 10minutes. Treatments using the enzyme/surfactant compound result inreduced wear and tear on the filter membranes.

[0041] Yet another application of the enzyme/surfactant compound is inconnection with filtration membranes used to eliminate the use ofsecondary clarifiers in wastewater treatment systems. In such systems,the enzyme/surfactant compound is introduced in, or prior to, theaeration basin. The filtration membranes are also placed in the aerationbasin, but are placed in a quiescent zone within the basin. The benefitsof using the enzyme/surfactant compound in these systems are: 1) toincrease metabolic activity during the aerobic process, 2) to increaseoxygen uptake, thus reducing aeration power requirements and costs, 3)to reduce biomass production, and 4) to reduce or eliminate biofoulingof the filtration membranes.

[0042] Accordingly, the systems and methods described herein achieveimproved reduction of biofilms and other benefits. While the abovedescription has focused primarily on crossflow filtration systems, andparticularly reverse osmosis systems, it is believed that theenzyme/surfactant compound is useful in reducing biofilms wherever theymay occur.

[0043] Thus, the compounds, systems and methods of the present inventionprovide many benefits over the prior art. While the above descriptioncontains many specificities, these should not be construed aslimitations on the scope of the invention, but rather as anexemplification of the preferred embodiments thereof. Many othervariations are possible.

[0044] Accordingly, the scope of the present invention should bedetermined not by the embodiments illustrated above, but by the appendedclaims and their legal equivalents.

What is claimed is:
 1. A method for reducing biofilm in an aqueoussystem, comprising the steps of: providing a mixture containing enzymesand surfactants, and introducing the mixture to an aqueous systemcontaining biofilm.
 2. The method of claim 1, wherein said mixturecomprises enzymes from one or more of the classes including esterases,lipases, proteases, glycosidases, cellulases, cellobiases, andphosphatases.
 3. The method of claim 2, wherein said mixture compriseslysozyme.
 4. The method of claim 2, wherein said mixture comprisesesterase (C-4), esterase-lipase (C-8), cystine arylamidase,chymotrypsin, beta galactosidase, beta glucuronidase, andnaphthol-AS-BI-phosphohydrolase.
 5. The method of claim 1, wherein saidmixture comprises nonionic surfactants from one or more of the classesincluding alkanolamides, amine oxides, block polymers, ethoxylatedprimary and secondary alcohols, ethoxylated alkylphenols, ethoxylatedfatty esters, sorbitan derivatives, glycerol esters, and polymericsurfactants.
 6. The method of claim 5, wherein said mixture comprises aC₁₂-C₁₆ linear alcohol ethoxylate surfactant.
 7. The method of claim 1,wherein said mixture comprises anionic surfactants from one or more ofthe classes including ethoxylated amines, ethoxylated amides,sulfosuccinates and derivatives, sulfates of ethoxylated alcohols,sulfates of alcohols, and polymeric surfactants.
 8. The method of claim7, wherein said mixture comprises a sodium alkyl ether sulfatesurfactant.
 9. The method of claim 1, wherein said mixture comprises thefermentation product of a yeast selected from the group consisting ofSaccharomyces cerevisiae, Kluyveromyces marxianus, Kluyveromyces lactis,Candida utilis (Torula yeast), Zygosaccharomyces, Pichia, and Hansanula.10. The method of claim 9, wherein said mixture further comprises one ormore nonionic surfactants from the group comprising alkanolamides, amineoxides, block polymers, ethoxylated primary and secondary alcohols,ethoxylated alkylphenols, ethoxylated fatty esters, sorbitanderivatives, glycerol esters, and polymeric surfactants.
 11. The methodof claim 9, wherein said mixture further comprises one or more anionicsurfactants from the group comprising ethoxylated amines, ethoxylatedamides, sulfosuccinates and derivatives, sulfates of ethoxylatedalcohols, sulfates of alcohols, and polymeric surfactants.
 12. Themethod of claim 9, wherein said mixture further comprises a C₁₂-C₁₆linear alcohol ethoxylate surfactant and a sodium alkyl ether sulfatesurfactant.
 13. The method of claim 12, wherein said fermentationproduct is present in said mixture at a concentration of from about 5.0%by weight to about 60.0% by weight, and said mixture is added to theaqueous system to obtain a concentration by weight of the mixture offrom about 0.1 part per million to about 25 parts per million.
 14. Themethod of claim 12, wherein said fermentation product is present in saidmixture at a concentration of from about 5.0% by weight to about 50.0%by weight, and said mixture is added to the aqueous system to obtain aconcentration by weight of the mixture of from about 1 parts per millionto about 5 parts per million.
 15. The method of claim 1, wherein saidaqueous system is a crossflow filtration system.
 16. The method of claim15 wherein said crossflow filtration system is a reverse osmosis system.17. The method of claim 15, wherein said mixture comprises thefermentation product of a yeast selected from the group consisting ofSaccharomyces cerevisiae, Kluyveromyces marxianus, Kluyveromyces lactis,Candida utilis (Torula yeast), Zygosaccharomyces, Pichia, and Hansanula.18. The method of claim 17, wherein said mixture further comprises oneor more nonionic surfactants from the group comprising alkanolamides,amine oxides, block polymers, ethoxylated primary and secondaryalcohols, ethoxylated alkylphenols, ethoxylated fatty esters, sorbitanderivatives, glycerol esters, and polymeric surfactants.
 19. The methodof claim 17, wherein said mixture further comprises one or more anionicsurfactants from the group comprising ethoxylated amines, ethoxylatedamides, sulfosuccinates and derivatives, sulfates of ethoxylatedalcohols, sulfates of alcohols, and polymeric surfactants.
 20. Themethod of claim 17, wherein said mixture further comprises a C₁₂-C₁₆linear alcohol ethoxylate surfactant and a sodium alkyl ether sulfatesurfactant.
 21. The method of claim 20, wherein said fermentationproduct is present in said mixture at a concentration of from about 5.0%by weight to about 60.0% by weight, and said mixture is added to thereverse osmosis system to obtain a concentration by weight of themixture of from about 0.1 part per million to about 25 parts permillion.
 22. The method of claim 20, wherein said fermentation productis present in said mixture at a concentration of from about 5.0% byweight to about 60.0%by weight, and said mixture is added to the reverseosmosis system to obtain a concentration by weight of the mixture offrom about 1 parts per million to about 5 parts per million.
 23. Themethod of claim 12, wherein said fermentation product is present in saidmixture at a concentration of from about 5.0% by weight to about 60.0%by weight, and said mixture is added to the aqueous system to obtain aconcentration by weight of the mixture of from about 1% to about 2%. 24.The method of claim 23 wherein the system temperature is 100° F. orhigher.
 25. The method of claim 24 comprising the additional step ofremoving the mixture containing enzymes and surfactants from the aqueoussystem within 10 minutes of said introducing step.